重复异常

Question

I am using an exception in my code below. I want to be able to repeat the question until they enter the correct value which is a double or int value. My problem is at when I ask for a value the second time. What should I change or use to fix this?

do{   
    try{
        System.out.println("Enter number");
        number = Double.parseDouble(br.readLine());      
    } catch(Exception ex) {
        System.out.println(ex +"\nEnter an int or double value");
        number = Double.parseDouble(br.readLine());             
    }
} while(false);

Output:

Enter number

qwe

java.lang.NumberFormatException: For input string: "qwe"

Enter an int or double value

we

Exception in thread "main" java.lang.NumberFormatException: For input string: 

"we"

    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1241)

    at java.lang.Double.parseDouble(Double.java:540)

    at practicedd.PracticeDD.main(PracticeDD.java:38)

Java Result: 1

Answer 1

Your second parseDouble is not in a try/catch, so nothing gets caught. Also, your while(false) will only let this execute the first time. Does this work for you? Also, you could do a while(true) and break after the parseDouble.

Double number = null;

do{
try{


System.out.println("Enter number");
number = Double.parseDouble(br.readLine());

}catch(Exception ex){
    System.out.println(ex +"\nEnter an int or double value");
}
}while(number==null);

} }

Answer 2

Your code is almost right. First, you need to change the condition of the while loop, and also, you need to break out of it

do{   
    try{
        System.out.println("Enter number");
        number = Double.parseDouble(br.readLine());
        break;      
    } catch(Exception ex) {
        System.out.println(ex +"\nEnter an int or double value");
        number = Double.parseDouble(br.readLine());             
    }
} while(true);